Development of a risk-based mine closure cost calculation model

The mining industry, as with many other industries all over the globe, has to face new challenges. One of these challenges is the everincreasing stricter social and environmental legislation and environmental awareness of the community in which it operates. From the early seventies, a number of Acts* were passed in South Africa, of which the most significant environmental legislation was the Environment Conservation Act (ECA), Act 73 of 1989. This Act provides a general structure for management activities. The next Act, which together with the ECA forms the basis of today’s environmental management, was the National Environmental Management Act (NEMA), Act 107 of 1998. This Act took management principles from the ECA a step further and mainly focused on comprehensive environmental management1. There are a number of principles contained in these and other Acts that govern the way mining companies should operate. As an example, ‘cradle-to-grave’ is one of the principles included in NEMA, which implies consideration, investigation, and analysis of all aspects in the life cycle of a product, process, or service. This principle is being implemented through various frameworks of which ISO 14040 is one example2. Further environmental legislation is contained in the new Mineral and Petroleum Resources Development Act (Act 28 of 2002), which requires that an environmental management and rehabilitation programme be in place before new-generation mineral rights are granted. Regulations 53 and 54 of this Act describes the methods, as well as the quantum of financial provision. The primary concerns for decommissioning and rehabilitation are to ensure public safety and health, and environmentally stable conditions compatible with the surrounding environment, and consequently minimize the environmental impacts caused by mining. The overall objective is to have socially, economically, and environmentally sustainable development. For example, the objectives of mine closure as set out in the South African Department of Minerals and Energy (DME) policies are: ➤ Safety and health of animals and humans must be safeguarded ➤ Environmental damage and residual impacts must be minimized to a level acceptable to all parties, i.e. avoidance of future pollution ➤ Land must be rehabilitated to as close to natural state as possible, i.e. creation of a stable land surface ➤ Physical and chemical stability of remaining structures must be such that they are not affected by natural elements ➤ Mines are closed effectively and costefficiently ➤ Mines are not abandoned, but closed in terms of policy. Development of a risk-based mine closure cost calculation model